Question: The military group of which the Air Defense Artillery is a branch was unprepared for the invasion of the territory the Nazis occupied. The country of this group was the only communist country to have an embassy where?

Passages:
The 1939 German ultimatum to Lithuania was an oral ultimatum which Joachim von Ribbentrop, Foreign Minister of Nazi Germany, presented to Juozas Urbšys, Foreign Minister of Lithuania on 20 March 1939. The Germans demanded that Lithuania give up the Klaipėda Region (also known as the Memel Territory) which had been detached from Germany after World War I, or the Wehrmacht would invade Lithuania. The Lithuanians had been expecting the demand after years of rising tension between Lithuania and Germany, increasing pro-Nazi propaganda in the region, and continued German expansion. It was issued just five days after the Nazi occupation of Czechoslovakia. The 1924 Klaipėda Convention had guaranteed the protection of the status quo in the region, but the four signatories to that convention did not offer any material assistance. The United Kingdom and France followed a policy of appeasement, while Italy and Japan openly supported Germany, and Lithuania was forced to accept the ultimatum on 22 March. It proved to be the last territorial acquisition for Germany before World War II, producing a major downturn in Lithuania's economy and escalating pre-war tensions for Europe as a whole. Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903 members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903 all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and, when activated, as a reserve of the U.S. Army under the authority of the President. In 1968, Tito offered Czechoslovak leader Alexander Dubček to fly to Prague on three hours notice if Dubček needed help in facing down the Soviets. In April 1969, Tito removed generals Ivan Gošnjak and Rade Hamović in the aftermath of the invasion of Czechoslovakia due to the unpreparedness of the Yugoslav army to respond to a similar invasion of Yugoslavia. Because of its neutrality, Yugoslavia would often be rare among Communist countries to have diplomatic relations with right-wing, anti-Communist governments. For example, Yugoslavia was the only communist country allowed to have an embassy in Alfredo Stroessner's Paraguay. One notable exception to Yugoslavia's neutral stance toward anti-communist countries was Chile under Pinochet; Yugoslavia was one of many countries which severed diplomatic relations with Chile after Salvador Allende was overthrown. Yugoslavia also provided military aid and arms supplies to staunchly anti-Communist regimes such as that of Guatemala under Kjell Eugenio Laugerud García.

Supporting sentences:
Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. In April 1969, Tito removed generals Ivan Gošnjak and Rade Hamović in the aftermath of the invasion of Czechoslovakia due to the unpreparedness of the Yugoslav army to respond to a similar invasion of Yugoslavia. For example, Yugoslavia was the only communist country allowed to have an embassy in Alfredo Stroessner's Paraguay.