Complex sentence: Franck then took the report to Washington, DC, where the Interim Committee met on June 21 to re-examine its earlier conclusions; but it reaffirmed that there was no alternative to the use of the bomb on a military target.
Split into simpler sentences: Franck then took the report to Washington, DC, where the Interim Committee met on June 21 to re-examine its earlier conclusions. However, the committee reaffirmed that there was no alternative to the use of the bomb on a military target.