During his first two years at the Ministry of Foreign Affairs in Rome, he served as a protocol officer assigned to visits by Italian government officials abroad.

By the mid-nineties globalisation and new challenges to international security underscored the need for major reforms of the UN bodies, a cause that Italy championed in all the UN fora.

[9] Within the EU and NATO, Minister Terzi was a strong advocate for a renewed "Pratica di Mare" partnership with the Russian Federation in order to settle energy and rule of law issues, as well as European security concerns raised from east–west diverging positions on conventional and nuclear forces.

At the same time, Minister Terzi did strive for a closer EU political, economic, and scientific cooperation with Israel and for the reactivation of the peace process on the basis of the two-state solution.

[12] Having India formally rejected all Italian proposals for convening UNCLOS Arbitration, Terzi on 11 March 2013 announced – on behalf of and in agreement with the government – that the two Italian marines, Massimiliano Latorre and Salvatore Girone – who had meanwhile been sent back to Italy having obtained from the Indian authorities a "temporary leave" to exert their electoral duties – would not have left the country to return to India until the arbitration established by UNCLOS[13] decided on the matter of jurisdiction.

The Indian reaction leads to growing tensions until on 21 March the Prime Minister's Office reversed Terzi's policy and announced the decision to send the two back to India.

[16] Three days later, on 26 March 2013 – as soon as the plenary session of the Chamber of Deputies reconvened to discuss the latest developments on the case – Terzi announced in parliament his resignation because of his dissent with the position of the government which had reversed a previously agreed decision of keeping the two Marines in Italy until the UNCLOS arbitration would have deliberated on the matter of jurisdiction.

[19][20][21] In a 27 March 2013 address to the Italian parliament, Monti revealed that Terzi repeatedly hampered efforts to settle the dispute with India in a quiet manner by perpetuating controversies through hawkish statements posted on Twitter.

On 29 March 2013 Terzi unveiled during a TV interview the heavy pressures he had received in order to give his consent to the return of the two Italian marines to India.

[31][non-primary source needed] In 2015 Terzi is appointed together with General Vincenzo Camporini to the Commission of Inquiry and Control of the High-level Group on Operation Protective Edge (Israel's 2014 war on Gaza).