LISA DESJARDINS: Today, in Cambodia's capital, soldiers arrived to a hero's welcome after they were released from five months of captivity by neighboring Thailand.

There's a tenuous cease-fire between those two countries.

It is one of eight conflicts that President Trump has claimed to have solved since he began his second term.

Those range from tensions tackled in his first term, to ongoing diplomatic disputes, to wars where he has personally helped negotiate cease-fires.

One of those is between Azerbaijan and Armenia, bitter rivals since the collapse of the Soviet Union.

Their leaders met the president in the Oval Office this summer.

Special correspondent Simon Ostrovsky and producer Katia Patin traveled to the Armenian border with Iran to assess whether that agreement could lead to peace facilitated by a corridor named after President Trump himself.

SIMON OSTROVSKY: A picturesque river valley cuts through the Caucasus Mountains, on one side, the Islamic Republic of Iran, on the other, Armenia, a country that was recently defeated in a war with Azerbaijan.

An uneasy peace has held since an agreement was signed in Washington in August backed by Trump.

But the deal's survival depends on Azerbaijan gaining access to this strip of Armenian territory along Iran's border.

That's because these Armenian lands separate Azerbaijan from its enclave of Nakhchivan, currently reachable only by air or overland through Iran.

Enter the Trump Route for International Peace and Prosperity, known as TRIPP, a proposal to turn this high-security border zone into a transit corridor for rail and road traffic linking Azerbaijan to Nakhchivan.

This railway line has been abandoned since the outbreak of war between Armenia and Azerbaijan, and the agreement reached between the two countries with the help of the Trump administration could dramatically alter the geopolitical map of this strategic region.

But there are still a lot of hurdles to get over before the White House's vision of peace becomes a reality on the ground here in Armenia on the border with Iran.

As with many Trump foreign policy initiatives, this deal isn't just about transport or cessation of hostilities.

It envisions a raft of commercial opportunities, including a U.S.-Armenian joint venture that will operate the Trump Route on a for-profit basis, an A.I.

data center powered by Nvidia chips and Dell servers, cooperation on nuclear energy.

And, in Azerbaijan, ExxonMobil plans to explore for gas.

But there are complexities to overcome.

The region's terrain presents significant engineering challenges, and the proposed corridor would operate right under the nose of Iran, which the Trump administration bombed recently.

On top of that, Armenia outsources its border security to Russia under a mutual defense treaty, something we found out the hard way when a Russian patrol stopped to check our paperwork.

MAN (through translator): What's your agency called again?

SIMON OSTROVSKY: PBS.

MAN (through translator): It's American, correct?

At this time, I'm issuing a warning.

SIMON OSTROVSKY: Your warning has been received.

We just got stopped by a Russian FSB Border Patrol.

They actually manned this border on behalf of Armenia, and they let us off with a warning, said that we shouldn't be filming so close to the border, but they were really interested in what we were doing here.

The Trump Route for international Peace and Prosperity is supposed to be manned by American contractors to manage this route.

Are they going to have to contend with the Russian border guards here as well?

And how's that going to work?

I think that that hasn't been figured out yet, and it's just one of the challenges that this peace plan still faces.

This American proposal is just the latest in a series of developments that have marginalized Russian influence in the South Caucasus.

Russian peacekeepers were swept aside when Azerbaijan took control of the disputed Nagorno-Karabakh enclave in 2023.

Stretched thin by its war in Ukraine, Moscow didn't intervene, a decision that led to the exodus of Karabakh's Armenian population.

Russia's role inside Armenia appears now to be at risk too, as polls show public sentiment towards Moscow plummeting.

This Armenian resident of the border area told me he felt betrayed and wanted Russian troops out under any future settlement.

KARLOS KHACHATARYAN, Resident (through translator): They're traitors, not allies.

SIMON OSTROVSKY: TRIPP is about much more than a regional transport link.

It's the critical missing segment in a proposed European corridor known as the Middle Passage, which would open Western trade routes to Central Asia, a region rich in rare earth minerals and other resources.

A direct connection through NATO ally Turkey would allow the five landlocked Central Asian states to avoid routes through Russia, China or Iran.

Officials from both Armenia and Azerbaijan seem eager to play up the commercial potential for America.

Here's Hikmet Hajiyev, assistant to the president of Azerbaijan.

HIKMET HAJIYEV, Assistant to the President of Azerbaijan: But the United States companies and United States private sector will also get a tremendous opportunity and using this route entering Central Asian market and including the rare earth material and some other business activities, a therefore win-win situation for everybody, including the United States companies.

SIMON OSTROVSKY: Armenia's Deputy Foreign Minister Vahan Kostanyan argues that a U.S.

pledge of $145 million in financial support, which includes funding for TRIPP and for enhancing Armenia's border capacities, is part of what will help make any peace more durable.

VAHAN KOSTANYAN, Armenian Deputy Foreign Minister: There is an agreement between Armenian and U.S.

government that we will be establishing a joint company together, which will have a right to develop infrastructure.

It has a huge potential for regional, but also global logistic change.

SIMON OSTROVSKY: What's clear is that a lot of the details still have to be worked out, but peace, if it sticks, would benefit Azerbaijan and Armenia and the wider region.

There is one big loser, of course, and that's Russia.

As America's footprint increases in the South Caucasus, Russia's will decrease, and it seems like Moscow is already on the back foot.

VAHAN KOSTANYAN: According to the agreement that Armenia and Russia signed back in the '90s, simultaneously, when Armenian border guards will increase their capacities, the number of Russian border keepers should be decreased.

And we already have these examples.

SIMON OSTROVSKY: I'm just still a little bit confused about what's going to happen to the Russians.

They're staying or not staying?

VAHAN KOSTANYAN: We are on or off.

SIMON OSTROVSKY: Relations with Russia are obviously a sensitive topic.

Yerevan doesn't want to anger its longtime ally prematurely.

But since the signing of the agreement in Washington, the Trump administration has achieved something Russia never could, an end to the skirmishes that plagued the Armenian-Azerbaijani border until last summer.

HIKMET HAJIYEV: I will divide the regional history in two parts, until the 8th of August and after the 8th of August.

A lot of things have tremendously changed in the region of the South Caucasus.

Since the independence of Armenia and Azerbaijan, these two countries were literally in a war.

But now we have real peace on the ground.

SIMON OSTROVSKY: Time will tell if TRIPP ever gets built or if a final peace settlement ending the war is ever signed.

But, for now, it appears the U.S.

is seizing an opportunity to reshape a region long dominated by Moscow.

For the "PBS News Hour," I'm Simon Ostrovsky in Meghri, Armenia.