Interior ministers from Europe and Central Asia vowed in Vienna this week to work more closely to tighten border security throughout the region.

International members of the Central Asia Border Security Initiative agreed Tuesday to step up efforts to stem the flow of illegal migrants, terrorists and illegal drugs through the region at a time when the pending withdrawal of NATO forces in Afghanistan is likely to present new security challenges.

A porous and undelineated border between Afghanistan and Tajikistan presents a major threat for the rest of Central Asia and areas beyond, mainly from drug smugglers seeking to export heroin into Europe from Afghan poppy fields, the U.N. Office on Drugs and Crime says.

The agency estimated thousands of pounds of heroin crosses the Afghan-Tajik border every year, sometimes accompanied by violent armed clashes and kidnappings along the border.

With the exit of the NATO-led International Security Assistance Force from the Afghanistan in 2014, fears the Kabul government can't or won't do enough to fight the drug trade have risen.

Nikolai Bordyuzha, secretary-general of the Russia-led Collective Security Treaty organization, said last week the NATO troop withdrawal will worsen the situation with drugs and terrorism in Central Asia region, TASS reported.

UNODC Executive Director Yury Fedotov and interior ministry officials from Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, Afghanistan, the European Union, Russia and the United States agreed Tuesday to "further enhance border management cooperation with neighboring countries at both strategic and technical levels."

"Developing effective border controls and countering drugs trafficked from Afghanistan is one of the key challenges for the countries of Central Asia," Fedotov said.

He encouraged Central Asian border control and law enforcement agencies to cooperate more closely, not only among themselves, but also with Afghanistan and neighboring countries.

Another key Central Asia Border Security Initiative member, the Organization for Security and Cooperation in Europe, also issued a strong endorsement of the Vienna declaration.

"There is a need for additional, specific assistance in the field of border security and management in light of the anticipated withdrawal of (ISAF) from Afghanistan," OSCE Secretary-General Lamberto Zannier said.

"Our primary objective remains the necessity to keep borders open and secure, while facilitating trade and the free movement of persons," he added.

The initiative seeks to build the skills of customs and border officials and to help facilitate border patrolling and surveillance, export control and national border strategy development in the region.

Another goal of international security efforts is to fight widespread corruption.

"Corruption, red tape, and security concerns on both sides of the (Afghanistan-Tajikistan) border" remain major problems in the region, Geoffrey Pyatt, principal deputy assistant U.S. Secretary of State for South and Central Asian affairs, told the Vienna gathering.

He said U.S. Secretary of State Hillary Clinton's vision for a "new Silk Road" linking Afghanistan with Central Asia trough trade and economic development "is only possible on the basis of real domestic reform, anti-corruption efforts, and predictable business and regulatory environments."

Security -- especially "the integrity of borders and transit corridors necessary for trade" -- is a key element of the U.S. policy, Pyatt said.