PODGORICA, - U.S. Secretary of State Mike Pompeo began a short trip to two small Balkan countries, Montenegro and North Macedonia, on Friday to discuss their roles in the Western NATO alliance.The streets in the Montenegrin capital Podgorica through which Pompeo's motorcade passed were cordoned off by police.Flying in from Rome, Pompeo became the most senior U.S. official to visit Montenegro since independence in 2006. He was set to be the most senior U.S. official to visit North Macedonia since 2000 in a stopover later in the day before flying on to Athens.Pompeo was met by Montenegrin Foreign Minister Srdjan Darmanovic at the airport, and due to meet President Milo Djukanovic later on.Pompeo's trip to Southern Europe has been overshadowed by an impeachment inquiry at home against President Donald Trump.Pompeo has yet to comment on evidence presented in the probe on Thursday in which it was revealed that the former U.S. special representative for Ukraine negotiations, Kurt Volker, thought it was "crazy" to withhold military aid from Kiev as it confronted a threat from Russia.However, Republican lawmakers said the evidence presented fell far short of a "quid pro quo" - exchanging or withholding U.S. assistance according to whether Ukraine helped damage Trump's political rival, Democratic Senator Joe Biden.At a camera spray at the start of a meeting with Montenegrin Prime Minister Dusko Markovic and Darmanovic, Pompeo did not respond when asked by a journalist if he thought Volker had acted appropriately in the case.SECURITY ISSUESU.S. officials said Pompeo would discuss security issues, given that Montenegro joined the U.S.-led NATO alliance in 2017 and North Macedonia's membership is expected to be ratified by the end of the year."The focus here is on NATO allies number 29 and 30," a senior State Department official said in previewing the trip for journalists last week."It underscores the importance of the NATO enlargement, the open-door policy.""And of course, in both countries, I think, we will talk about Russian efforts to sow discord there," the official said, recalling allegations of Russian involvement in a coup attempt in Montenegro in 2016 and interference in North Macedonia's effort to resolve its long-running feud with Greece.Two Russian intelligence officers and two opposition politicians were among 13 people sentenced on Thursday over a 2016 election day plot aimed at toppling Montenegro's government, killing the prime minister and bringing a pro-Russian alliance to power.Moscow has repeatedly dismissed accusations about its role as absurd and all the accused denied wrongdoing.The verdict said that one of the aims of the coup attempt was to prevent Montenegro, which became independent in 2006 after splitting from Serbia, from joining NATO. Montenegro also wants to join the European Union.North Macedonia's attempts to integrate with Western institutions were hampered until it agreed with its neighbor Greece last year on its new name. Greece had long insisted that "Macedonia," the name the country chose after the breakup of Yugoslavia, implied a territorial claim on the Greek region of that name.