Apart from the issue of assistance to Ukraine, trying to convince countries to bolster NATO's eastern flank, especially the Baltic countries, has been one of the most difficult tasks for diplomats over the past few months, he said.
According to the minister, Lithuania's defenses should be particularly strengthened because of its geographical position: its closeness to Russia's Baltic Sea exclave of Kaliningrad and its long border with Belarus.
"Discussions are still ongoing. We have no clear promises about what will be done and how much will be done," he told reporters after the Vilnius Russia Forum in the district of Trakai, not far from the capital.
In Landsbergis' words, the issue of beefing up the Baltic defenses is "deeper rooted" in how countries see the new European security architecture after Russia's invasion of Ukraine.
The Baltic countries want to be sure that "every inch of NATO territory, as the US president has said, is defended in a real and practical way", according to Lithuania's top diplomat.
"This is what we are seeking. There is no such clear understanding yet, because it seems to me that there is some expectation among states that perhaps the violations, despite the ongoing war and everything that is happening in Ukraine, are not so deep and maybe some normalization is possible, and then perhaps such reinforcement is not necessary," the minister said.
"We are talking not only about practical things, such as how many and what kind of tanks and troops are needed and where, but also about a certain difference in attitudes about what has happened here," he added.
At NATO's Madrid summit in June, Lithuania expects NATO to adopt decisions to beef up the region's defenses.
The Baltic countries want the Alliance's multinational battalions in the region to be increased to brigade-sized units.